In recent years, there has been a rapid spread of display devices using display media such as liquid crystals, organic EL (electroluminescence), and inorganic EL. Among these display devices, active-matrix display devices have been widely used because they are fast in response speed and make it easier to display multiple tones.
An active-matrix display device includes: an active-matrix substrate, on which a large number of pixels are arranged in a matrix manner; and a counter substrate placed in such a way as to face the active-matrix substrate.
The active-matrix substrate is larger in area than the counter substrate. The active-matrix substrate and the counter substrate are joined to each other by a sealing agent (not illustrated) extending along the edge of the counter substrate. Sandwiched between the active-matrix substrate and the counter substrate is a display medium layer constituted by any one of the various display media named above.
The active-matrix substrate has a plurality of scanning wires and a plurality of signal wires so arranged inside of a cell surrounded by the sealing agent as to intersect with one another. Provided near each of the intersections between the scanning wires and the signal wires is a pixel section having a TFT (thin-film transistor).
The active-matrix substrate has a region in its peripheral part that runs off the edge of the counter substrate. Provided in the region is a connection area including (i) drawn wires constituted by metal wires drawn from the pixel sections provided inside of the cell and (ii) terminal areas (terminal electrodes). Such a display device requires a connection of each TFT to an external drive circuit such as a driving integrated circuit.
A connection of each TFT to an external drive circuit is made by connecting the terminal electrode to a flexible wiring board, such as a TCP (tape carrier package), on which a driving integrated circuit has been mounted. Such a terminal electrode is connected to a flexible wiring board, generally, by using an ACF (anisotropic conductive film).
However, generally, due to mounting constraints, there is a distance of several millimeters between a region between the active-matrix substrate and the counter substrate in where the sealing agent is provided and a position on the connection area to which the ACF is attached. Therefore, the metal wires are exposed in the region between the region where the sealing agent is provided and the position to which the ACF is attached. For this reason, in this region, moisture, foreign bodies, etc. are likely to adhere to the metal wires, thus undesirably corroding the metal wires.
Accordingly, as methods for solving such a problem, the techniques described in Patent Literature 1 and Patent Literature 2 have been proposed, for example.
FIG. 21 is a cross-sectional view showing a configuration of a connection area on an active-matrix substrate described in Patent Literature 1.
As shown in FIG. 21, the active-matrix substrate includes: a glass substrate 301; a lower metal wire 302 drawn from a display section to a connection area provided at an end of the glass substrate 301; an interlayer insulating film 303 (planarizing film) covering the lower metal wire 302; a contact hole 304 formed in the interlayer insulating film 303; an upper metal wire 305 formed on the interlayer insulating film 303 and connected to the lower metal wire 302 through the contact hole 304; a transparent conductive film 306 entirely covering the upper metal wire 305; a protective insulating film 307, formed on the transparent conductive film 306, which has an opening provided in a terminal area (terminal electrode) of the upper metal wire 305. Connected to the terminal area by an ACF 310 is a copper foil wire 312 of a flexible wiring board 311.
In Patent Literature 1, corrosion of the metal wire formed under the transparent conductive film 306 is prevented by removing that part of the upper metal wire 305 which is neither protected by the protective insulating film 307 nor the ACF 310.
Further, FIG. 22 is a plan view showing a configuration of a connection terminal area on an active-matrix substrate described in Patent Literature 2.
As shown in FIG. 22, the active-matrix substrate includes: a glass substrate 401; scanning wires 402 provided on the glass substrate 401; a counter substrate 411; and a sealing agent 412 provided between the glass substrate 401 and the counter substrate 411, the scanning wires extending from pixel sections into an area outside of the sealing agent 412. Each of the scanning wires 402 has an end that serves as a terminal electrode 403 (gate input terminal) for use in connection with an external flexible wiring board 420 constituted by a polymer film or the like.
In Patent Literature 2, by forming slits 404 in an exposed part of each scanning wire 402 outside of the sealing agent 412, the exposed part of the scanning wire 402 is separated into plural parts.
Thus, in Patent Literature 2, the slits 404 suppress the progression of corrosion caused by immersion of the scanning wire 402 in dewdrops or the like.